I'm new to doing mods on pistols. I have however built a few ARs so I'm not mechanically inept. My question is what mods should I look to do first? What are the best mods for the best bang for the buck?

extend every thing polish every thing in the trigger and 3.5 connector

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"I won't be wronged, I won't be insulted, and I won't be laid a hand on. I don't do these things to other people and I expect the same from them."
Get Yourself A Glock And Lose That Nickel Plated Sissy Pistol!".... Tommy Lee Jones in "U.S. Marshall's".

extend every thing polish every thing in the trigger and 3.5 connector

+1, tho I personally only like the slide release lever extended. But I'm not doing any competition shooting.

__________________Assumption is the mother of all ****ups.Know what you know, Know what you don't know. -Paul Pedzolt"Jack of all trades, master of none, though oftentimes better than master of one" -Mynshul

1. Change the sights. I can't stand the factory rear sight, and I don't like the fact that they are plastic.

2. Change out the OEM slide lock lever for the extended. Makes locking the slide back for malfunction clearing much easier.

3. Polish the trigger assembly. Only do this if you ware comfortable with it and know what you're doing. If you search for ".25 cent Glock trigger job" on youtube, quite a few vids should pop up.

I'm not a fan of the 3.5 connectors. For one, I don't want that light of a trigger, but my main problem with them is all the ones I've tried have made the trigger mushy and not break as cleanly. Your experience may differ though.

-Fred

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"Breathe when you can, shoot when you should."
-Rob Leatham

Hello I'm new here, although I own other brand handguns, I came here first because I'm really becoming obsessed with Glocks. Recently purchased the Glock 19 Gen4 and have made a few mods to it.
1. First I changed the sights for my bad eyes. Went with the XS Big Dot. Not for bulls eye shooting but for getting on target fast, you can't beat it and is still fairly accurate. Wife likes it too.
2. I did have a few stove pipes and brass in the face in the first 200-300 rounds. My spring assembly is stamped 0-4-1, Glock told me I need the 0-4-3 and my ejector was stamped 336 and they said I need the one stamped 30274. It has more of a blunt end. So they are sending those to my dealer free and I will install them. (I just like doing it myself).
3. I did install the 3.5lb. connector and what a difference! At 15 yards my grouping went from wide to tight. It really is just a little mushy till you get to the last stage and then its nice smooth and crisp and goes Bang!. I don't know how much the pull dropped but I don't think about 1 lb. Really did not expect it to make much difference but when I got to the range, discovered a huge difference in my groups.
4. Although Glock is sending the 0-4-3 spring assembly, I did go ahead and ordered a SS guide rod and single 18lb spring. Action seems smoother.
5. I ordered a Sepra plug and installed it. I did spend about 20 minutes with the dremel to make it fit perfect. But it's there and the holes plugged. I just could not get use to having that open hole, it got on my nerves.
6. Good for Gen4...I'm a lefty so I did move the mag release to the right side.
7. And installed the medium backstrap for my big hands.
8. I love the 19 but buying the 17 Gen4 next week. Fits my big hand much better. My wife is taking the 19.